This invention relates to the field of collimators for use in cameras of the radiation or gamma ray type. A subject to be investigated is infused with a radioactive substance which emits radioactive or gamma rays. The camera includes a transducer to receive the gamma rays and record an image therefrom. In order for the image to be a true representation of the subject being investigated, a collimator having collimating apertures is positioned between the transducer and the subject to screen out all of the radioactive rays except those directed along a straight line through the collimating apertures between a particular part of the subject and a corresonding particular part of the transducer. The collimator is made of a radiation opaque material such as lead, and collimating apertures have been formed therein by various means such as drilling holes therethrough. Another construction previously known was to sandwich corrugated strips of lead foil between flat strips, much the same as corrugated cardboard construction. When attempting to make a focusing collimator using the sandwiched corrugated strip type of construction, one of the problems was inability to make all the rows of apertures focus at a point axially aligned with the central axis of the collimator. In such construction, each corrugated strip was substantially identical. The apertures of each row would focus at a common point the same distance from the strip, and if merely stacked one on top of the other, the focal points of each row would be spaced apart in vertical alignment the same distance in front of the collimator rather than focusing at a point in axial alignment with the central axis of the collimator. In an attempt to partially solve this problem, one end of a telescoping arm was hinged on a pivot point representing a common focal point in axial alignment with the central axis of the collimator. On the other end of the telescoping arm, a weighted forming block was positioned to bear against the top of each sandwiched row of corrugated strips as one was laid on top of the other to make the collimator. As pressure was applied to the weighted forming block, each row was tilted slightly to direct its apertures toward the pivot point on which the telescoped arm was hinged representing a centrally disposed focal point axially aligned with the central axis of the collimator. However, if the pivot point was spaced far enough from the central axis of the collimator for the focal point of the central or middle row apertures to coincide therewith, then since the focal point of every row of apertures is the same distance from its respective corrugated strip, the top most row would come to its focal point before reaching the pivot point on which the telescoped arm was hinged. The same would be true of the bottom most row, and of each row between the central one and those above or below. As a result, the focal points of each row of apertures would still be spaced apart in a vertical plane rather than focusing on points in axial alignment with the central axis of the collimator.